Cable brake for overhead door



Sept 1968 R. H. NEISEWANDER 3,399,710

CABLE BRAKE FOR OVERHEAD DOOR Filed Jan. 25, 1967 2 Sheets-Sheet 1 I N VENTOR.

RAY H. NEISEWANDER ATT'YS Sept. 3, 1968 Filed Jan. 25, 1967 R. H. NEISEWANDER CABLE BRAKE FOR OVERHEAD DOOR 2 Sheets-Sheet 2 INVENTOR: RAY H. NEISEWANDER fia gq' z,ai%,aallm a mg n T I Ys United States Patent M 3,399,710 CABLE BRAKE FOR OVERHEAD DOOR Ray H. Neisewander, 1010 Edwards St., Springfield, Ill. 62703 Filed Jan. 25, 1967, Ser. No. 611,659 2 Claims. (Cl. 160-201) ABSTRACT OF THE DISCLOSURE A cable brake for overhead door which brings the door to rest in the raised position so that the door may be closed by exerting only a generally downward pulling force without exerting a substantial outward pulling force. The cable brake is secured adjacent the top of the lowermost section or panel of the door and includes a sheave positioned in a U-shaped channel extending transversely to the door. The lifting cable is reeved about the sheave and confined therein by the side channels.

Background of the invention Overhead doors generally are designed to travel along a guide track which has a horizontally extending portion and a vertically extending portion.

The lifting cable associated with the garage door is preferably secured to the door at the bottom thereof in order that stresses created in the door by forces exerted on the cable are limited to the bottom of the door. For example, when the operator lowers the door by grasping a pull rope fastened to the bottom of the lower section of the door, the pressures exerted in the door through the rope and cable tend to offset each other. This would not be true if the cable were secured to the door at a point spaced from the bottom thereof. The resultant stresses would tend to tear the door apart.

When the door is raised, however, it will not come to rest until the point at which the cable is secured to the door reaches that point along the path of travel of the door which is nearest to the cable rewind drum. In this position the door is positioned almost entirely on the horizontally extending portion so that the door may be fully retracted above the top of the door opening even when the space between the top of the door opening and the ceiling of the room is less than the height of the door. However, because the door is positioned on the horizontally extending portion of the guide track when it is in its raised position, a substantial outward pulling force is needed to close the door in addition to the downward pulling force. In the past, this difficulty has been solved by providing a relatively long horizontal portion of the guide track extending well above the door opening. However, this solution may be applied only in cases where the room ceiling is quite high.

Summary Use of the inventive cable brake will allow an overhead door to come to rest in its raised position above the door opening but in such a position that the door may be closed by exerting almost an entirely downward pulling force. When the door is raised, it will come to rest at a point at which the lifting cable extends generally perpendicularly to the guide track. At this point, the lowermost section of the door extends generally vertically, and the door may be closed by exerting a pulling force having a minimum outward component.

Description of the drawing FIG. 1 is a side view in fragmentary cross section showing the door in the lowered position and its associated guide track;

3,399,710 Patented Sept. 3, 1968 Referring now to FIG. 1, the numeral 10 designates a door frame and the numeral 11 designates a side Wall of the structure supporting the guide track 12. A similar guide track is provided at the opposite side of the door frame 10. The guide track 12 includes a generally vertically extending portion 12a and a generally horizontally extending portion 12b and is provided with the usual inwardly-turned flanges 13 for supporting and guiding the rollers 14 in the track.

Garage door 15, which is composed of panels 16 having front and rear surfaces 17 and 18, respectively, and sides 19, is secured to rollers 14 by means of brackets 20. Adjacent panels are connected by means of hinges 21.

Lifting cable 22 is secured at one end thereof by pin 23 to the lowermost portion of the door at its side 19, and the other end of lifting cable 22 is wound about the usual rewind drum 24 which is mounted on spring-wound axle 25 rotatably mounted in side walls 11.

Secured to the upper portion of bottom panel 16a, is cable brake 26. Referring now to FIGS. 3-5, cable brake 26 is seen to include base portion 27, having openings 28 for attachingthe cable brake to the rear surface 19 of the door 15 by means of screws, bolts, or other suitable means. Extending perpendicularly to base portion 27 and transversely of panel 16a is U-shaped channel portion 29 having sides 30 and 31 and bottom 32. Side 31 bears against side 19a of panel 16a of the door, and bottom 32 advantageously extends adjacent the front side 17a of panel 16a. Inserted between the sides of channel portion 29 is sheave 33 held in place by grommet 34, which may be extruded from side 30.

Cable brake 26 may advantageously be formed from a single generally triangular sheet of steel which may be folded to form the base portion and channel portion.

As can be best seen in FIGS. 1 and 3, when the garage door is in its lowered position, lifting cable 20 is positioned in groove 35 of sheave 33 and extends through channel portion 29 between the sides thereof. Referring now to FIG. 2, when the door is in its raised position, the lifting cable extends from rewind drum 24 around sheave 33 to pin 23 at the bottom of the panel 16a.

Operation When it is desired to raise the door from its closed position, the operator grasps the usual handle provided at the bottom of panel 16a and exerts an upward lifting force to move the door upwardly along guide track 12. Spring-wound rewind drum 24 exerts a pulling force on cable 22, and this lifting force is transmitted to the door at the bottom thereof through pin 23. As the door is raised, the pulling force of cable 22 is always transmitted to the door at the bottom thereof.

Lifting cable 23 will continue to be wound about rewind drum 24 until sheave 33 reaches its point of closest approach to the rewind drum along its path of travel. The upward momentum of the door will carry the sheave slightly beyond this point and the cable will unwind from rewind drum 24 against the force of the rewind spring. The door will eventually be urged to its rest point, shown in FIG. 2, by the tension of the spring and its resistance to unwinding. At such rest point, the portion of the lifting cable 19 between rewind drum 24 and sheave 33 is generally perpendicular to guide track 12. The portion of lift cable 22 between sheave 33 and its point of attachment to panel 16a always remains generally parallel with panel 16a, and the force exerted on panel 16a by the lifting cable is principally transmitted through the length of the panel in a direction generally tangential to guide track 12, thereby urging the door to travel along the track. If the cable extended directly from rewind drum 24 to pin 23, a large component of the force exerted by the cable would tend to pull the panel from the guide track and create undesirable stresses.

As seen in FIG. 2, the cable brake brings the door to rest at such a point along the guide track 12 that the bottom of the door is adjacent the top of door frame 10. In that position of the door the spring is still under a state of tension but is prevented from fully unwinding because movement of the door in either direction will only serve to increase its tension. Hence, the rewind spring supplied a positive holding force for maintaining the door in a raised position.

If the cable brake were not provided, the rest point of the door in the raised position would be such that the lifting cable would extend from the rewind drum to pin 23 generally perpendicular to the guide track. In this position a substantial downward pulling force is needed to close the doors. In order to overcome this disadvantage door frames have in the past been provided with a horizontal guide track which extended well above the door opening. This construction, however, could be used only in a high-ceilinged building.

The inventive cable brake brings the door to rest so that the bottom panel 16a is disposed generally vertically. Thus, when the door is to be closed, only a generally downward pulling force need be exerted rather than a force having both a large outward component and a downward component. When the door is at its rest point, part of the weight of the door is supported by the generally horizontally extending portion 12:: of guide track 12, and part of the door weight is supported by the lifting cable 22. If a rewind spring is used that has a pulling force at the rest point equal to, or greater than, the portion of the door weight that is supported by the lifting cable, the door will always come to rest at the same point. Thus, even a rewind spring having a very large spring constant may be used, and the door will never come to rest at a point substantially above the opening height. As the door is pulled downwardly to its closed position, greater tension is put on the rewind spring and a correspondingly greater force is exerted on the door by the rewind spring, but this greater force is less than the increased weight that the lifting cable is required to support by virtue of the door moving from the horizontally extending portion 12b to the vertically extending portion 12a of the guide track.

The invention finds particular utility when used on relatively large commercial and industrial doors. The door openings in commercial structures are usually substantially higher than, say, the opening in a home garage. In the past, if it were desired to close the door with only a substantially downward pulling force, the door would have to extend vertically above the door opening for a substantial distance, thereby necessitating an increase in the height of the ceiling of the room. The size and Weight of large commercial doors also makes it desirable to be able to close them without exerting too much of a wasted outward force. The invention allows such large doors to be easily closed without requiring an excessive distance between the top of the door opening and the ceiling.

While in the foregoing specification a detailed description of an illustrative embodiment was set forth for the purpose of explanation, it is to be understood that many of the details hereingiven may be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. In an overhead door structure having a door frame, a pair of guide tracks on said frame, each of said guide tracks having a generally vertically extending portion and a generally horizontally extending portion, a door slidably mounted in said guide tracks for movement therealong, the movement of said door along said tracks defining a path of door travel, said door comprising a plurality of hingedly joined panels having front and rear surfaces and opposite sides, a spring-wound drum mounted on said frame, the improvement comprising a cable brake attached to one of said door panels, said cable brake including a generally U-shaped channel portion positioned along a side of said one panel and opening toward the rear of said one panel, a lifting cable attached to said door adjacent the bottom thereof and extending upwardly through said channel to said drum, said door being movable between raised and lowered positions, said cable brake being closest to said drum along the path of door travel when the door is in the raised position, said cable being wound on said drum as the door moves from the lowered position to the raised position, said cable brake pulling said cable away from said drum as the door moves beyond the raised position, whereby the door is urged to rest in the raised position by said spring-wound drum.

2. The structure of claim 1 in which the lowermost panel of said door is generally vertical when the door is in the raised position.

References Cited UNITED STATES PATENTS 1,815,749 7/1931 Warner -191 2,007,552 7/ 1935 Vetterlein 160189 X 2,274,216 2/ 1942 Sanders l60190 2,291,583 7/1942 Rowe 160190 2,538,626 1/1951 Olsen 160-201 2,786,523 3/1957 Phillips l60191 2,786,712 3/1957 Whiting 160-191 X FOREIGN PATENTS 556,751 10/1943 Great Britain.

DAVID J. WILLIAMOWSKY, Primary Examiner.

DENNIS L. TAYLOR, Assistant Examiner. 

